Pigment. Dark brown-black, dense, conspicuous, in forebody medially between eye-spots and pharynx; brown-black, diffuse, may be present between pharynx and ventral sucker; brown-black lines may be present on hindbody along ventral margin of keel and in two longitudinal lines lateral to keel on each side; golden brown, oblong, either side of tail base ( Figure 1 a
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). In life, pigment in forebody and lines on hindbody blueblack.

Cercarial emergence: rhythm and variation. Cercariae emerged in large numbers with variable periods between emergences (few days to weeks), sometimes emerging on consecutive days; emergence generally between 7 pm and 8 am.

Behavior. Naturally emerged cercariae are free-swimming and swim actively toward light where they orient themselves facing away from the light source. When swimming, the hindbody is folded ventrally and the forebody is highly contracted longitudinally ( Figure 1 c
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); the tail lashes from side to side for movement. When resting, the hindbody is slightly flexed dorsally; tail extending backwards and angled ventrally from hindbody ( Figure 1 d
View Figure
). When first emerged, cercariae swim actively towards light and frequently rise to the surface after which they settle on their side or ventral side up. After about 24 hours cercariae become less active, decaudation may occur and they start to die. The cercariae never encyst.